title: Formation and aggregation of lipid rafts in γδ T cells following stimulation with Mycobacterium tuberculosis antigens.
abstract: Lipid rafts are plasma membrane microdomains that are implicated in diverse signaling pathways in immune cells. Based on the distinct types of T-cell receptors, two T-cell subpopulations have been identified: αβ and γδ T cells. In humans, γδ T cells represent a relatively rare T lymphocyte population but play a critical role in the immune response to infection by Mycobacterium tuberculosis. It has been demonstrated that Mycobacterium tuberculosis antigens (Mtb-Ag) preferentially activate γδ T cells. Thus, we investigated whether lipid rafts are involved in the Mtb-Ag-mediated activation of γδ T cells. Human peripheral blood mononuclear cells (PBMCs) were stimulated with Mtb-Ag, and expression of a lipid raft marker ganglioside GM1 (GM1) was determined by flow cytometry. The aggregation of lipid rafts was evaluated by laser confocal microscopy. Non-stimulated fresh PBMCs minimally expressed GM1 (6.55 ± 2.01%) and had no aggregated rafts in γδ T cells. Mtb-Ag stimulation gradually increased the expression of GM1 in a time-dependent manner. At 72 h, the majority of γδ T cells expressed GM1 (88.69 ± 7.55%). Furthermore, accompanied with the increased expression of GM1, aggregation of lipid rafts became gradually visible in γδ T cells. The aggregated rafts, however, were not evenly distributed and only occurred over a small portion of GM1-positive cells. Pretreatment with methyl-β-cyclodextrin, a cholesterol-depleting reagent, completely inhibited the Mtb-Ag-mediated aggregation of lipid rafts. These results demonstrate that lipid raft aggregation occurs in Mtb-Ag-activated γδ T cells, suggesting that lipid rafts are involved in activation of γδ T cells.
authors.affiliation: Central Laboratory, the First Affiliated Hospital of Bengbu Medical College, Anhui, PR China.
authors.forename: He-Zuo
authors.initials: HZ
authors.lastname: Lü
authors.forename: An-You
authors.initials: AY
authors.lastname: Zhu
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.forename: Bai-Qing
authors.initials: BQ
authors.lastname: Li
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D002469:Cell Separation; D005434:Flow Cytometry / Q000379:methods; D016650:Fluorescein-5-isothiocyanate; D005677:G(M1) Ganglioside / Q000096:biosynthesis; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D021962:Membrane Microdomains / Q000737:chemistry*; D018613:Microscopy, Confocal / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D013997:Time Factors; D047392:beta-Cyclodextrins
chemical_list: D000942:Antigens, Bacterial; D016692:Receptors, Antigen, T-Cell, gamma-delta; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C072681:Mycobacterium tuberculosis antigens; D005677:G(M1) Ganglioside; D016650:Fluorescein-5-isothiocyanate